1. Field of the Invention
This invention relates to gas insulated switchgears, and more particularly to such switchgears including a plurality of containers each accommodating a disconnector for disconnectably connecting line cables to a main line via an interrupter, etc.
2. Description of the Related Art
FIG. 1 shows a typical organization of a conventional gas insulated switch device including disconnectors for disconnectably connecting line cables to a main line via an interrupter, etc. In the figure, two containers 20 and 21 separated from each other by a central distance L.sub.1 are connected to each other by means of a connection tank 15 attached to the windows 42 and 43 formed at upper portions of the two containers 20 and 21 respectively. The container 20 and the connection tank 15 are coupled to each other via an electrically insulating spacer 15A, while the container 21 and the connection tank 15 are coupled to each other via a electrically insulating spacer 15B. For simplicity, FIG. 1 shows only two containers 20 and 21; however, in actual service, further number of containers are connected in succession via connection tanks similar to the tank 15. At the upper portion of the container 20 are disposed connection conductors 13B and 14B; at the upper portion of the container 21, on the other hand, are disposed connection conductors 13D and 14D. The connection conductors 13B and 13D are electrically coupled to each other by means of a conductor 13C which is disposed within the connection tank 15 to extend through the electrically insulating spacers 15A and 15B; in a similar manner, the connection conductors 14B and 14D are connected to each other by means of a connection conductor 14C extending within the connection tank 15. Further, the connection conductors 13B and 14B extend, toward left in the figure, through an electrically insulating spacer 15C, to be coupled to connection conductors 13A and 14A, respectively, and thence to be led out into another container which is omitted in the figure.
At the bottom portion of the container 20 are disposed a first system of line cables 12A and 12B, at whose top ends are disposed contacts 30A and 30B of a first disconnector; the connection conductors 13B and 14B are provided with co-acting contacts 33B and 34B of the first disconnector, which are driven by means of a driving mechanism (not shown) to be brought into contact with the opposing contacts 30A and 30B, respectively, of the first disconnector. Further, on the top ends of a second system of line cables 11A and 11B disposed within the container 21 are provided contacts 31A and 31B; they are brought into contact with the co-acting contacts 33D and 34D disposed on the connection conductors 13D and 14D. Grounding devices 9 and 10 are provided with contacts 9A and 10A, which are driven by a driving device (not shown) to ground the line cables 11A and 11B and the line cables 12A and 12B, respectively, when necessary. The interior spaces within the containers 20 and 21 and the connection tank 15 are filled with an electrically insulating gas (SF.sub.6 gas) for maintaining the electrical insulation therein.
In the gas insulated switch device constituted as described above, at side portions of the containers 20 and 21 are formed windows 41 and 42, respectively, for attaching test tanks thereto. Tests of the device are conducted when, for example, the device is first installed or when a failure occurs; during the usual service time when tests are not conducted, the windows 41 and 42 are sealed by means of closure plates 40A and 41A, respectively.
FIG. 2 shows the state in which a test tank 19 is attached to the window 41 of the container 20. Test conductors 17 are disposed on the panel 18 of the test tank 19, wherein it is possible, for example, to connect the ends of the conductors 17 to the line cables 12A and 12B as shown in FIG. 2, so as to Conduct a withstanding voltage test of the cables 12A and 12B. During this test, the detachable conductors 27A and 27B of the cables 12A and 12B shown in FIG. 1 are detached.
The above described switch device, however, has the following disadvantages. Namely, respective containers 20 and 21 are provided with respective test windows 41 and 42, so that the test tank 19 can be attached to either one of the windows 41 and 42. The test tank 19 requires a certain horizontal length L.sub.2 for its attachment, due to the length of the test conductors 17 thereof. The central distance L.sub.1 is provided for making possible the attachment of the test tank to each container. During service time, however, the space between the containers constitutes a dead space, which increases the whole dimension of the gas insulated switch device so that a large installation area is required.